The main function of piston ring is seal, heat conduction, oil control and bearing. Piston ring prevent gas leakage from cylinder, transfer part of heat from piston to cylinder liner. The real contact cylinder wall is piston ring in piston kit. It fill the gap between piston and cylinder wall and seal the combustion chamber. Piston ring is the most easy to wear in engine parts. Although it is just a Flat metal ring with incision, it plays a vital role in engine power stroke. Its performance influence directly the dynamic property, economical efficiency and environment of internal combustion engine.